How the mind shapes action: Offline contexts modulate involuntary episodic retrieval

Involuntary retrieval of previous stimulus–response episodes is a centerpiece of many theories of priming, episodic binding, and action control. Typically it is assumed that by repeating a stimulus from trial n–1 to trial n, involuntary retrieval is triggered in a nearly automatic fashion, facilitating (or interfering with) the to-be-executed action. Here we argue that changes in the offline context weaken the involuntary retrieval of previous episodes (the offline context is defined to be the information presented before or after the focal stimulus). In four conditions differing in cue modality and target modality, retrieval was diminished if participants changed the target selection criterion (as indicated by a cue presented before the selection took place) while they still performed the same task. Thus, solely through changes in the offline context (cue or selection criterion), involuntary retrieval can be weakened in an effective way.     

Dissociation of binding and learning processes

A single encounter of a stimulus together with a response can result in a short-lived association between the stimulus and the response [sometimes called an event file, see Hommel, Müsseler, Aschersleben, & Prinz, (2001) Behavioral and Brain Sciences, 24, 910–926]. The repetition of stimulus–response pairings typically results in longer lasting learning effects indicating stimulus–response associations (e.g., Logan & Etherton, (1994) Journal of Experimental Psychology: Learning, Memory, and Cognition, 20, 1022–1050]. An important question is whether or not what has been described as stimulus–response binding in action control research is actually identical with an early stage of incidental learning (e.g., binding might be seen as single-trial learning). Here, we present evidence that short-lived binding effects can be distinguished from learning of longer lasting stimulus–response associations. In two experiments, participants always responded to centrally presented target letters that were flanked by response irrelevant distractor letters. Experiment 1 varied whether distractors flanked targets on the horizontal or vertical axis. Binding effects were larger for a horizontal than for a vertical distractor-target configuration, while stimulus configuration did not influence incidental learning of longer lasting stimulus–response associations. In Experiment 2, the duration of the interval between response n – 1 and presentation of display n (500 ms vs. 2000 ms) had opposing influences on binding and learning effects. Both experiments indicate that modulating factors influence stimulus–response binding and incidental learning effects in different ways. We conclude that distinct underlying processes should be assumed for binding and incidental learning effects.

     

Fear of Infection or Justification of Social Exclusion? The Symbolic Exploitation of the Ebola Epidemic

Public discourse in Western countries on the 2014 Ebola epidemic provided a unique natural opportunity to study the relationship between a disease's sociocultural representation and health policy support. Our main prediction stated that among Western citizens, support for restrictive health policies (e.g., mandatory quarantining) would be determined more through preexisting prejudice towards African immigrants than fears of Ebola infection. A questionnaire study with time‐lagged measurement of predictor and criterion variables employing a German sample (N = 218) that was heterogeneous in terms of gender, age, profession, political orientation, and income level provided clear support for this assumption. Although variables related to fear‐of‐infection were significant predictors, prejudice‐related variables explained several times more variance in participants’ support for restrictive policies. Moreover, the degree to which participants adopted prevalent beliefs regarding the sociocultural origins of Ebola (e.g., eating bushmeat) further intensified the impact of prejudice‐related variables.     

Hierarchical organization of a reference system in newborn spontaneous movements

In this paper, we studied spontaneous newborn movements regarding the coordination of the four limbs, arms and legs, from a dynamic perspective. We used the method of recurrence plots to analyse the kinematic data from audiovisual recordings of neonates. We identified temporal and spatial synchronization of the four limbs that resulted in high recurrence patterns of biomechanical reference configurations. Furthermore, we identified transitions between linear and nonlinear epochs in the movement behavior of newborns on different time scales by means of recurrence quantification analysis. Results are discussed in the context of the concept of a structural hierarchy, in which different time scales correspond to hierarchical levels of organization.     

At your own peril: An ERP study of voluntary task set selection processes in the medial frontal cortex

A tool that is commonly used to investigate selection among different alternatives in a changing environment is the task-switching paradigm. Functional neuroimaging has pointed out a role for the posterior medial frontal cortex and the posterior parietal cortex in the voluntary selection of task sets. In the present study, we set out to investigate the temporal dynamics of these agency-related processes (in task choice vs. no-choice conditions) using event-related brain potentials (ERPs). The results revealed agency-related modulations of a series of ERP components, including (1) an early parieto-occipital activation, taken to reflect the evaluation of choice versus no choice; (2) a subsequent medial frontal expression of the voluntary selection between task sets; (3) a CNV-like sustained negativity in preparation for the target; (4) a target-induced N210—P210 complex, taken to reflect early sensory-perceptual processing; and (5) a target-induced P3, associated with the evaluation of the stimulus and its designated response vis-à-vis the chosen versus competing task sets. Together, these results indicate that the opportunity to choose between tasks invokes activity originating from the medial frontal cortex, associated with voluntary task set selection, but also activation at different time points in a number of other brain areas, not necessarily captured by functional neuroimaging.     

Dissecting stimulus–response binding effects: Grouping by color separately impacts integration and retrieval processes

In selection tasks, target and distractor features can be encoded together with the response into the same short-lived memory trace, or event file (see Hommel, 2004), leading to bindings between stimulus and response features. The repetition of a stored target or distractor feature can lead to the retrieval of the entire episode, including the response—so-called “binding effects.” Binding effects due to distractor repetition are stronger for grouped than for nongrouped target and distractor stimulus configurations. Modulation of either of two mechanisms that lead to the observed binding effects might be responsible here: Grouping may influence either stimulus–response integration or stimulus–response retrieval. In the present study we investigated the influences of grouping on both mechanisms independently. In two experiments, target and distractor letters were grouped (or nongrouped) via color (dis)similarity separately during integration and retrieval. Grouping by color similarity affected integration and retrieval mechanisms independently and in different ways. Color dissimilarity enhanced distractor-based retrieval, whereas color similarity enhanced distractor integration. We concluded that stimulus grouping is relevant for binding effects, but that the mechanisms that contribute to binding effects should be carefully separated.     

The impact of MRI scanner environment on perceptual decision-making

Despite the widespread use of functional magnetic resonance imaging (fMRI), few studies have addressed scanner effects on performance. The studies that have examined this question show a wide variety of results. In this article we report analyses of three experiments in which participants performed a perceptual decision-making task both in a traditional setting as well as inside an MRI scanner. The results consistently show that response times increase inside the scanner. Error rates also increase, but to a lesser extent. To reveal the underlying mechanisms that drive the behavioral changes when performing a task inside the MRI scanner, the data were analyzed using the linear ballistic accumulator model of decision-making. These analyses show that, in the scanner, participants exhibit a slow down of the motor component of the response and have less attentional focus on the task. However, the balance between focus and motor slowing depends on the specific task requirements.     

(Not) Thinking about you: Differences in victims’ and perpetrators’ self-focus after interpersonal and intergroup transgressions

We tested the hypothesis that, following a transgression, victims and perpetrators differ in their focus of attention. In three studies (total N = 740), we manipulated participants’ social role (victim vs. perpetrator) in a hypothetical scenario (Studies 1 and 2) and in a perceived real conflict (Study 3) in an interpersonal (Studies 1 and 2) and an intergroup (Study 3) context. Results from all studies confirmed that victims show a stronger self-focus than perpetrators. Moreover, results suggest victims’ higher self-focus as a predictor of willingness to reconcile. Participants’ self-focus mediated the effect of social role on reconciliation intentions as a single mediator (Study 2), or in sequence with their motivation to consider the other party's needs (Study 3). Overall, the present research suggests that victims and perpetrators differ in their focus of attention, and that this difference has important theoretical and practical implications for reconciliation between individuals and between groups.